The Exogrid features bookmarks. They're pretty simple to use.
Simply tap or click the passage you'd like to set your bookmark on. Do the same again to clear your bookmark, or click anywhere else to move your bookmark.
Bookmarking also gives you a direct link to a given passage that you can share, just check the address bar for that.
If you ever can't find your bookmark, check the top of the page for a button to go to it.
That's all there is to it! Happy reading.